Ultrastructural findings in oral Kaposi's sarcoma (AIDS)

Occurrence of tubuloreticular structures and intracisternal paracrystalline inclusions in endothelial cells of tissue from different epidemiological types of Kaposi's sarcoma

Biopsied tissue specimens from 40 cases of classic, atypical classic, endemic, and AIDS-associated Kaposi's sarcoma (KS) were investigated by electron microscopy. To search for ultrastructural differences between non-AIDS-associated KS and AIDS-associated KS, the occurrence of the following 2 ultrastructural abnormalities of the rough-surfaced endoplasmic reticulum in KS cells was evaluated semi-quantitatively: tubuloreticular structures (TRS) and intracisternal paracrystalline inclusions (IPI). These peculiar structures were found in 23 of the 40 KS cases. Two types of TRS could be distinguished: loose TRS (LTRS) and compact ones (CTRS). LTRS were observed in endothelial cells of tissue from all the different epidemiological types of KS. CTRS were confined to AIDS-associated KS. IPI were present in endothelial tumor cells of only 3 non-AIDS-associated KS cases. The study shows that in cells of KS tissue only CTRS, but not LTRS, are an ultrastructural marker for AIDS-associated KS.

Kaposi sarcoma-associated herpesvirus (KSHV) induces heme oxygenase-1 expression and activity in KSHV-infected endothelial cells

Kaposi sarcoma (KS) is the most common AIDS-associated malignancy and is characterized by angiogenesis and the presence of spindle cells. Kaposi sarcoma-associated herpesvirus (KSHV) is consistently associated with all clinical forms of KS, and in vitro infection of dermal microvascular endothelial cells (DMVECs) with KSHV recapitulates many of the features of KS, including transformation, spindle cell proliferation, and angiogenesis. To study the molecular mechanisms of KSHV pathogenesis, we compared the protein expression profiles of KSHV-infected and uninfected DMVECs. This comparison revealed that heme oxygenase-1 (HO-1), the inducible enzyme responsible for the rate-limiting step in heme catabolism, was up-regulated in infected endothelial cells. Recent evidence suggests that the products of heme catabolism have important roles in endothelial cell biology, including apoptosis and angiogenesis. Here we show that HO-1 mRNA and protein are up-regulated in KSHV-infected cultures. Comparison of oral and cutaneous AIDS-KS tissues with normal tissues revealed that HO-1 mRNA and protein were also up-regulated in vivo. Increased HO-1 enzymatic activity in vitro enhanced proliferation of KSHV-infected DMVECs in the presence of free heme. Treatment with the HO-1 inhibitor chromium mesoporphyrin IX abolished heme-induced proliferation. These data suggest that HO-1 is a potential therapeutic target for KS that warrants further study.

Faecal alpha 1 antitrypsin as a marker of gastrointestinal disease in HIV antibody positive individuals

Hypoalbuminaemia and diarrhoea are common complications of HIV infection and substantial causes of morbidity, but the specific intestinal pathologies that cause enteric protein loss have not been clearly defined. Two hundred and twenty stool samples from patients with a variety of HIV related conditions were analysed for faecal alpha 1 antitrypsin. Patients with intestinal Kaposi's sarcoma had a significantly raised faecal alpha 1 antitrypsin value and hypoalbuminaemia. A faecal alpha 1 antitrypsin value of greater than 0.3 mg/g wet stool has a sensitivity of 94% and a specificity of 76% for the diagnosis of intestinal Kaposi's sarcoma in HIV positive individuals. Patients with cytomegalovirus and bacterial enteritis had raised faecal alpha 1 antitrypsin values but levels were normal for all other intestinal pathologies compared with pathogen negative stool. The combination of faecal alpha 1 antitrypsin concentration greater than 0.2 mg/g, a negative stool culture for enteric bacteria, and the absence of palatal Kaposi's sarcoma has a sensitivity of 55% and specificity of 88% for the diagnosis of enteric cytomegalovirus infection.

HIV-related tumors of the oral cavity

In HIV-infected patients with AIDS the most frequent malignancies are Kaposi's sarcoma and non-Hodgkin's lymphoma. In these patients, the natural history of these tumors is quite different from those of HIV-negative subjects. These tumors may present atypical clinical aspects, may be very aggressive, and the coexistence of immunosuppression and opportunistic infections may render their treatment more difficult. The aim of this article is to provide updated information on the epidemiology, pathogenesis, natural history, and management of tumors that develop in the oral cavity of patients with AIDS.

Oral Kaposi's sarcoma: a 10-year retrospective histopathologic study

Microscopic diagnosis of early Kaposi's sarcoma continues to be a challenge to the pathologist, as does the identification of bacillary angiomatosis (BA) which may have a similar appearance. 120 oral Kaposi's sarcoma (KS) biopsies submitted to the UCSF oral pathology service from 1981-1991 were reviewed in order to describe the clinical-pathologic spectrum of these lesions and to search for unrecognized cases of BA. Also, histopathologic features of oral KS were compared to 30 oral pyogenic granulomas, and immunohistochemical stains for endothelium-associated CD34 antigen were done. The diagnosis of KS was confirmed in all biopsies and no cases of BA were found. Histologically, the KS specimens exhibited numerous features that separated them from pyogenic granulomas, and could themselves be divided into two clinical-pathologic subtypes: small, well-delineated macular lesions (31), which were characterized by inconspicuous patches of spindle cells containing ill-defined vascular spaces; and larger, infiltrative nodular lesions (89), which were characterized by spindle cells lining vascular slits and bizarre-shaped vessels. Extravasated RBCs were evident in almost all KS lesions; hemosiderin deposits and hyaline globules were seen in half of each of the small and large lesions. Nuclear atypia was minimal and mitotic activity was slight. Lymphocytes in small lesions added to the difficulty of microscopic interpretation of these incipient lesions. CD34 was expressed on all spindle cells lining vascular spaces in larger lesions and on spindle cells of small, subtle lesions. We conclude that within the spectrum of lesions that are diagnosed as oral KS, two clinical-pathologic types can be identified: macular small spindle-cell lesions and nodular infiltrative vascular lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Neoplastic disease in the head and neck of patients with AIDS

Immunosuppression increases the risk of developing malignancies. In immunosuppression due to human immunodeficiency virus (HIV) disease the common head and neck tumors are Kaposi's sarcoma and non-Hodgkin's lymphoma. Squamous cell carcinoma has also been reported. Kaposi's sarcoma is the commonest neoplastic disease in AIDS. The incidence of lymphoma is rapidly increasing. This article reviews the incidence, clinical presentation and management of these diseases in the head and neck in AIDS patients.

Head and neck malignancies associated with HIV infection

Immunosuppressed persons are at greater risk of developing malignancies. In human immunodeficiency virus (HIV) immunosuppression the most common oral cancers are Kaposi's sarcoma and non-Hodgkin's lymphoma. Squamous cell carcinoma has also been reported to be associated with HIV disease. Kaposi's sarcoma is the most frequent neoplastic disease in acquired immunodeficiency syndrome and is by far the most common in the head and neck area. This article reviews the prevalence, clinical features, and management of these diseases in HIV infection.

Immunoelectron microscopy shows an atypical pattern and a quantitative shift of collagens type I, III and VI in oral Kaposi's sarcoma of AIDS

The localization of collagen types I, III and VI in normal human alveolar and palatal mucosa and in oral Kaposi's sarcoma (KS) was studied by light microscopy and cryo-immunoelectron microscopy. Normal oral mucosa revealed two different types of organization. The upper connective tissue stroma contained a loose reticular network mainly composed of collagen types III and VI, while collagen type I immunostaining predominated in the deeper stroma. Ultrastructurally, in the KS tumour stroma, a loose pattern of individual thin collagen fibrils was noted. These often fanned out at their ends showing a filamentous substructure. The fibrils consisted predominantly of collagen type I similar to individual fibrils of normal oral mucosa. However, there was a marked loss of thick fibre bundles of collagen types I and III in KS compared with normal oral mucosa, whereas collagen type VI was markedly increased and found preferentially in clusters and strands around cross-striated fibrils that often spanned the distance between single collagen fibres. The abundance of collagen type VI in a pattern similar to early stages of wound healing suggests that the KS stroma resembles an early organizational stage of the interstitial and vascular extracellular matrix subject to a high rate of collagen turnover. This character of the KS stroma appears to result from a continuous auto-and paracrine stimulation of cell growth and collagen synthesis and provides an excellent model to study the structural arrangement of collagen type VI in relation to the fibrillar collagen types I and III.

Distribution of basement membrane-associated heparan sulfate proteoglycan in idiopathic and AIDS-associated Kaposi's sarcoma

In the present study we analyzed the immunohistochemical distribution of different major basement membrane (BM) components with special emphasis on the BM-associated heparan sulfate proteoglycan (HSPG) in early and late stages of Kaposi's sarcoma (KS), both of idiopathic and AIDS-associated origin. In early KS all BM components tested were found surrounding the small clefts of tumour vessels. Heparan sulfate proteoglycan showed the weakest and often fragmented pattern of staining. In the late, nodular sarcomatous form of KS individual tumour cells were surrounded by a BM composed of collagen IV, laminin and fibronectin, while heparan sulfate proteoglycan was not detectable in most cases. Neither between idiopathic and AIDS-associated KS nor between cutaneous and visceral lesions were significant differences in the staining pattern. Our findings of a rather selective expression of various BM-components and the known distribution in normal blood and lymphatic capillaries raises the hypothesis that KS-cells may be derived from cells of lymphaticovenous differentiation.

Oral manifestations of HIV infection and their management. I. More common lesions

Oral lesions are common at all stages of HIV infection. This first of two articles reviews the clinical features and pathogenesis of common oral manifestations of HIV disease (candidiasis, hairy leukoplakia, Kaposi's sarcoma, and HIV-related periodontal disease) and considers current treatment measures.

Oral hairy leukoplakia in AIDS patients: an ultrastructural study

Hairy leukoplakia is a specific oral lesion associated with the opportunistic development of Epstein-Barr virus in the oral epithelium. It is now considered to be an early sign of HIV-induced immunosuppression. Four cases of oral hairy leukoplakia (OHL) from the lateral borders of the tongue of male AIDS patients were investigated by transmission electron microscopy. At the ultrastructural level, herpes-like viral particles were detected in the oral lesions of all cases. Indirect immunofluorescence performed on two cases showed the presence of EBV antigens in the nuclei and the cytoplasm of the infected epithelial cells. None of the specimens contained ultrastructural evidence of human papillomaviruses.

Ultrastructure of the jejunal mucosa in human immunodeficiency virus infection

The ultrastructural changes in the jejunal mucosa of 11 male patients, three with clinical AIDS, five with AIDS related complex-progressive generalized lymphadenopathy (ARC-PGL), and three who were only HIV antibody positive, were studied. In the enterocytes, major abnormalities were proliferation of smooth endoplasmic reticulum mitochondrial changes, vacuolization of cells, and fat hold up. In the lamina propria, degeneration of enteric nerve axons and smooth muscle were seen. Microvasculature showed both endothelial cell degeneration and hyperplasia. The presence of tubuloreticular inclusions in endothelial cells paralleled the stage of the disease. Since none of the 11 patients had any opportunistic infection, these changes are likely to be the effect of HIV infection.

Fine structure of EBV-infected keratinocytes in oral hairy leukoplakia

We evaluated biopsy specimens of 42 cases of clinically suspected oral hairy leukoplakia for the pattern and frequency of ultrastructural alterations specific to epithelial cells infected with Epstein-Barr virus. Some structures could clearly be identified as Epstein-Barr virus at different stages of assembly, but other intranuclear and cytoplasmic alterations were not conclusively identifiable as any known structure. Keratinocytes producing Epstein-Barr virus contained intranuclear particles of different size and shape; some of them were arranged in a monodispersed pattern and others formed arrays. In contrast, both lesional keratinocytes not producing virus and keratinocytes in uninvolved mucosa contained intranuclear particles reminiscent of perichromatin granules. The nuclei of productive cells also contained marginated chromatin, tubular structures, and, occasionally, crystalline and fibrillar formations as well as enveloped virus. Formations of electron-dense bilayers were seen on both sides of the nuclear membrane. In the cytoplasm of productive cells we observed aggregates of parallel tubules and enveloped electron-dense bodies. Although many of these observations are of diagnostic and pathobiological significance, the morphogenesis, composition, and function of alterations with uncertain morphological identification remain unclear.

Non-pigmented oral kaposi's sarcoma (AIDS). Report of two cases

In 90% of cases of AIDS-associated Kaposi's sarcoma (KS), the lesion is observed in the oral cavity. Oral KS usually reveals distinct clinical features characterized by a brown-bluish or otherwise pigmented appearance. The histological features are identical to classical KS. The occurrence of a non-pigmented oral KS in 2 male homosexual patients has prompted the present case reports. Clinicians should be aware that not all cases of AIDS-associated oral KS appear as brown or purplish tumors but may present without any discoloration.

Ultrastructural findings in clinically uninvolved oral mucosa of patients with HIV infection

Twelve biopsies of clinically normal oral mucosa taken from HIV seropositive patients have been investigated by means of light- and electron microscopy. Vascular abnormalities were found in all biopsies, regardless of the clinical stage of the HIV infection. In particular slit-like vascular channels, sparseness of intercellular junctions and swollen, protruded endothelial cells with an increased quantity of Weibel-Palade bodies were noticed. These findings were similar to those described in lesions of early stage Kaposi's sarcoma.

Ultrastructural and immunohistochemical findings in oral hairy leukoplakia

Three cases of HL from the lateral border of the tongue of male homosexual AIDS patients were investigated by thin section electron microscopy. Keratinocytes contained condensed chromatin in their pyknotic nuclei and a few organelles in the oedematous cytoplasm. Chromatin was in close association to the nuclear membrane and showed a punched-out appearance. Particles typical of the herpes virus group were abundant in the upper two thirds of the epithelium in all three cases. Virus particles were seen frequently in the nuclei of the ballooned keratinocytes, but rarely in cells containing Candida albicans. Viral nucleocapsids were observed budding at the inner nuclear membrane, thereby acquiring the prospective viral envelope. Complete, enveloped virions were found in the endoplasmic reticulum and in the extracellular space. These virions were identified immunohistochemically as Epstein-Barr virus (EBV) using two monoclonal antibodies directed against EBV capsid and membrane antigen, respectively. Candida albicans was observed in the stratum corneum and in the upper layer of the stratum spinosum. Special cytoplasmic tubular structures arranged in parallel bundles were found in koilocytotic cells in addition to characteristic membrane structures composed of undulating convoluted membranes. Epithelial basement membranes were always intact.

The extracellular matrix in oral Kaposi sarcoma (AIDS): the immunohistochemical distribution of collagens type IV, V, VI, of procollagens type I and III, of laminin and of undulin

Twelve oral AIDS-associated Kaposi sarcomas (KS) were studied for the distribution of extracellular matrix components using indirect immunofluorescence. Staining for basement membrane (BM) components revealed two distinct patterns of distribution: a delicate and partly fragmented lining of BMs around sinusoid-like vascular spaces or an occasional diffuse interstitial fluorescence in the tumour stroma; or an irregular broad rim of fluorescence in walls of larger blood vessels. These findings support a vascular cell origin of the endothelial- and spindle cell component in KS. The tumour stroma was almost completely negative for collagen type V and undulin, whereas an intensive fluorescence was noted for procollagens type I, III and collagen type VI. In areas adjacent to KS a loss of procollagens type I and III, collagens type V, VI and undulin was noted. An intimal sheath of collagen type V was usually absent from blood vessels of the tumour or the peritumourous connective tissue. Immunohistochemical findings indicate that the preexisting interstitial connective tissue matrix is destroyed during tumour invasion and that subsequently procollagens type I, III and collagen type VI are synthesized de novo by cells of the tumour stroma.